UK-POLOS.NET - THE VW Polo Forum

Leif wrote: Tue Jan 01, 2019 6:18 pm

monkeyhanger wrote: Tue Jan 01, 2019 3:52 pm

Chungster wrote: Mon Dec 31, 2018 1:44 pm
Filling up with BP Ultimate 97 now which seems to have helped the mpg a bit.



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I wouldn't waste your money buying higher octane fuel - Your car can't take advantage of it and isn't set up for it.

Higher octane fuel isn't appreciably.more calorific than regular RON95 (it's a common misconception that it is), but the additives such as Toluene, Ethanol, MMT and TMB reduce the volatility of the fuel, allowing it to be compressed further without self igniting (pinking).

If your engine isn't set up to run on higher octane, it won't compress it further on advanced timing. Your 1.0TSI does not run on a higher compression ratio to take advantage of higher octane (97-99) fuels, the Polo and Golf GTI 2.0TSI units don't either - the Golf R/Seat Leon Cupra/Audi S3 are optimised for high octane fuels.

If you run on higher Octane fuels you won't do any damage, but you are literally chucking money away and might actually see lower mpg as a result - lower volatility fuel ignited by a spark in a low compression ratio engine may not combust fully - that may be a problem for cars with a GPF - that GPF will be loaded for longer if your engine is chucking out I'm completely burned fuel as more soot than is expected. Loaded particulate filters increase back pressure and lower mpg.

If you think you're seeing a.modest increase on mpg then it's probably running in gains, a change in your commute (less traffic on the roads in the weeks leading up to Christmas has seen my mpg go up over the last 3 weeks) or the placebo affect because you think that RON97 fuel is more calorific (Ethanol is about 10% less calorific than petrol, and is a common RON enhancer).

I won’t argue with most of the above, you clearly know more than me, but the super fuels, whatever brand name they use, do have more detergents in them. Ordinary fuel has enough detergents to keep the engine clean, the super fuels have enough to clean the engine. This only applies to Shell, BP etc and not supermarket fuels, one reason to avoid the latter. Occasional use of the super fuels may be worthwhile, but obviously not most of the time.

monkeyhanger wrote: Tue Jan 01, 2019 9:39 pm I wouldn't dismiss all supermarket fuels - Tesco Ultimate RON99 is every bit as good as Shell V-power, and is marketed as having a large detergent quota. I was using it in my Golf R for 2 years without issue until my local Costco got a fuel station. I use Costco fuel - all variants claim to have plenty of detergents. I tried the RON99 Super Unleaded in the Polo that I use for the Golf R. It made no difference in the Polo for reasons I already mentioned, but it was worth a try as it was only 3p a litre dearer. When Shell, BP and Esso charge circa 12-15p a litre more for their super unleaded, it adds a lot to your fuel bill for no gain. BP and Esso Super is RON97 rather than RON99 and I can tell the difference between 97 and 99 in my Golf R - the 97 stuff being a little less responsive.

The standard fuel has enough detergent in it to keep the fuel system clean. Never been stung by contaminated fuel myself, but big name garages are just as likely to be a cause as supermarkets. The fuel is the same stuff from the same tankers The only variation is in the additives pack added at fill. I have seen Shell branded tankers filling up the local Tesco Extra petrol station.